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Full text of "Text Book Of Mechanical Engineering"

Forging a Box-key.                           113

mandril either now or afterwards (B). Heating the rest of the
bar the hook is bent to the correct form round the anvil beak c,
being constantly checked by rule and sheet iron template; and the
proper section given at the same time (shewn at r> D) by means
of set hammer or flat-face. Both these last-named operations
must go together, for the form of the hook will be more or less
spoilt by flattening to the section at D D, and this must be again
restored by bending.

Bolts in machinery are sometimes placed in very extra-
ordinary positions, so that the spanner in Fig. in may have to
be discarded, and the Box-key (represented in Fig. 115) used
in its place. It has a socket at A to fit the nut, and a shank at
&, on which a wrench (sketched at c) is placed when required.
The key is forged by making the A and B portions separately, and
afterwards welding them together. Thus, part A is made by
bending a strip of iron, which has been previously Scarfed at the
ends, into the form of the hollow cylinder D. This is done on
the anvil beak, and a second heat is necessary to weld it. The
piece B is next formed from a round bar of sufficient section to
give the square when flattened. It is shouldered on a swage as
at E, sufficiently small to fit into the ring D. And now the small
end of E and the cylinder D are both heated to welding tempera-
 ture; then, being" put together as at F, are riveted by striking the
mandril G, and by hammering round as at H. The fourth heat is
required to work out the square j with flat-face and anvil, and on
the fifth and last heat a mandril, which may be hexagonal or
square, as desired, is driven into the cylindrical portion K, and
the outside hammered until the Tequisite shape is given to the
hole. Removing the mandril the key is considered as finished.

Tongs, having to be used almost continually, are soon burnt
away by the fire, and the smith must be able to forge them as
needed. We will therefore describe the forging of the round-nosed
tongs sketched at B, Fig. 98. The ' bits? that grip the work are
made-first. For them a piece of square bar is to be set down on
the edge of the anvil until it receives the form A, Fig. 116; the
successive operations for this are shewn at i, 2, 3. The two bits
should not be made right and left-handed, but exactly alike, for
in turning one round axially it will be found to accommodate